mesh-controller/cmd/mesh-controller/hosts_behind_test.go

package main

import (
	"strings"
	"testing"

	"github.com/novox/mesh-controller/internal/inventory"
)

// A host refuses a declaration carrying a field it does not know, and refuses it whole — so every new
// field is a flag day, and the mesh had no record of which host any machine ran (novox/hq
// 04-ISSUES/087). The order was kept by somebody remembering it.

func TestTheMeshNamesWhichMachinesRunWhichHost(t *testing.T) {
	split := hostSplit([]inventory.Node{
		{Name: "anchor", HostVersion: "04a27ca"},
		{Name: "laptop", HostVersion: "ced54d4"},
		{Name: "spare", HostVersion: "04a27ca"},
	})
	if len(split) != 2 {
		t.Fatalf("two versions were reported and the split has %d: %v", len(split), split)
	}
	if got := strings.Join(split["04a27ca"], ","); got != "anchor,spare" && got != "spare,anchor" {
		t.Fatalf("04a27ca is held by %q", got)
	}
	if got := strings.Join(split["ced54d4"], ","); got != "laptop" {
		t.Fatalf("ced54d4 is held by %q", got)
	}
}

func TestTheMeshDoesNotClaimWhichHostIsNewer(t *testing.T) {
	// **The fault this replaced.** A host reports its version as a commit, and commits have no order.
	// The first version compared them as strings and, on the live mesh, named the three machines
	// running the NEWER host as the ones behind: `ced54d4` sorts above `04a27ca` and means nothing.
	//
	// There is no assertion to make about which is newer, and that is the point — the type says so.
	// hostSplit returns who runs what, and nothing that could be read as an ordering.
	split := hostSplit([]inventory.Node{
		{Name: "old-but-sorts-high", HostVersion: "ced54d4"},
		{Name: "new-but-sorts-low", HostVersion: "04a27ca"},
	})
	for version, machines := range split {
		if len(machines) != 1 {
			t.Fatalf("%s is held by %v", version, machines)
		}
	}
}

func TestAMachineThatHasNotSaidIsNotAVersion(t *testing.T) {
	// It may be running anything. Counting it as a version would invent a disagreement; `node show`
	// says per machine that it has not said.
	split := hostSplit([]inventory.Node{
		{Name: "anchor", HostVersion: "04a27ca"},
		{Name: "quiet"},
	})
	if split != nil {
		t.Fatalf("one reported version and one silence read as a disagreement: %v", split)
	}
}

func TestMachinesAgreeingOnTheirHostAreNotADisagreement(t *testing.T) {
	if split := hostSplit([]inventory.Node{
		{Name: "anchor", HostVersion: "v2"},
		{Name: "laptop", HostVersion: "v2"},
	}); split != nil {
		t.Fatalf("machines agreeing reported a split: %v", split)
	}
}

func TestAMeshWhereNothingReportedAHostStatesNoDisagreement(t *testing.T) {
	if split := hostSplit([]inventory.Node{{Name: "anchor"}, {Name: "laptop"}}); split != nil {
		t.Fatalf("a mesh told no host version reported a split: %v", split)
	}
}

func TestAReportedHostVersionIsKeptAndReadBack(t *testing.T) {
	// The machine has sent this since ADR 0141 and the controller's own copy of the report did not
	// have the field, so it was unmarshalled into nothing. End to end through the store, because the
	// fault was a field that existed on one side of the wire only.
	open := aMesh(t)
	record, err := open.inventory.NodeByName(t.Context(), "anchor")
	if err != nil {
		t.Fatal(err)
	}
	if record.HostVersion != "" {
		t.Fatalf("a machine that never reported one has host version %q", record.HostVersion)
	}
	if err := open.inventory.RecordHostVersion(t.Context(), record.ID, "ced54d4"); err != nil {
		t.Fatal(err)
	}
	again, err := open.inventory.NodeByName(t.Context(), "anchor")
	if err != nil {
		t.Fatal(err)
	}
	if again.HostVersion != "ced54d4" {
		t.Fatalf("the reported host version read back as %q", again.HostVersion)
	}
	// An empty report never clears what a machine last said: a bare word that the node is there says
	// nothing about its host.
	if err := open.inventory.RecordHostVersion(t.Context(), record.ID, "  "); err != nil {
		t.Fatal(err)
	}
	kept, err := open.inventory.NodeByName(t.Context(), "anchor")
	if err != nil {
		t.Fatal(err)
	}
	if kept.HostVersion != "ced54d4" {
		t.Fatalf("a report carrying no host version cleared what the machine had said: %q",
			kept.HostVersion)
	}
}